MIC 205 Exam #4: Bacterial Diseases of the Skin

Skin Microbiota normally are harmless microbes able to survive on the skin, what are they

1.) Bacteria:

• Gram-positive aerobic cocci belonging to Staphylococcus and micrococcus genera

• Gram-positive anaerobic bacilli, including variousdiphtheroids related to Corynebacterium diphtheriae

  Yeast: Malassezia

  • Microbes cannot be removed completely through regular cleaning

• Skin microbes may become opportunistic pathogens

Bacteria that infect the skin can cause

a wide range of diseases with mild to life-threatening consequences

Examples of Bacterial Diseases of the Skin

1.) Folliculitis

2.) Staphylococcal Scalded Skin Syndrome

3.) MRSA Infection

4.) Necrotizing Fasciitis

5.) Cat Scratching Fever

6.) Acne

7.) Pseudomonas Infections

8.) Gas Gangrene

Many viral diseases are systemic in nature, but

their signs and symptom are often expressed on the skin

Diseases caused by S. Aureeus

Follicultis

Styes

Carbuncles

Scalded Skin Syndrome

Impetigo

Toxic Shock Syndrome

Bacteremia

food poisoning

Pneumonia

3 Virulence Factors of Staphylococcal

1.) Enzymes

2.) Phagocytic Factors

3.) Toxins

Virulence Factors of Staphylococcal: Enzymes

Coagulase - forms fibrin clots

Lipase - breaks down lipids

B-Lactamase - breaks down B-lactams

Virulence Factors of Staphylococcal: Phagocytic Factors

Slime Layer- Promotes attachment

Protein A - Masks antibodies

Virulence Factors of Staphylococcal: Toxins

Cytolytic Toxins - disrupts cell membranes

Leukocidin - Disrupts leukocytes

TSS toxin - triggers fever, rash etc

Folliculitis

• red, swollen bump on the skin ( pimple)

• can occur at base of the eyelid (Sty)

• spread of the infection can produce furuncles and carbuncles

Folliculitis is caused by

Staphylococcus Sp.

Characteristics of Staphylococcus Sp.

1.) Facultatively Anaerobic - can tolerate sealed environment of “buried” hair follicel

2.) Salt tolerant - tolerate salty human skin

3.) Desiccation Tolerant - can survive on infectious surfaces ( fomites) and skin

4.) Transmission - Direct contact between individuals or individuals

Staphylococcal Scalded Skin syndrome

skin peeling

Signs and symptoms of Staphylococcal Scalded Skin Syndrome

• Cells of the outer epidermis separate from one another, and underlying tissue

• Outer skin layer peels off in sheets

Pathogen of Staphylococcal Scalded Skin Syndrome

Staphylococcus Aureus

Staphylococcal Scalded Skin Syndrome is caused by

Exfoliative Toxins

Exfoliative Toxins in Staphylococcal Scalded Skin Syndrome

The toxin will cause the dissolution of the cellular bridge protein that holds adjoining cells together of the epidermis

Blood will carry the toxin throughout the body

Septicemia

Toxins in the blood stream

Pathogenesis of Staphylococcal Scalded Skin Syndrome

• No scarring since the dermis is unaffected

• Death is rare, but may occur due to secondary infections, such as yeast

Epidemiology of Staphylococcal Scalded Skin Syndrome

• Diseases occurs primarily in infants or immune-suppressed individuals

• Transmitted by person-to-person ( usually direct contact) spread of bacteria

Diagnosis, Treatment, and Prevention of Staphylococcal Scalded Skin Syndrome

• Diagnosed by characteristic sloughing of the skin

• Treated by the administration of antimicrobial drugs

• Prevention is difficult due to the widespread occurrence of Staphylococcus aureus on the skin

Secondary Infections of Staphylococcal Scalded Skin Syndrome are

deadly

Methicillin-Resistant S. Aureus (MRSA): symptoms

• May start as small red bumps ( folliculi) that develop into deep, painful abscesses

• Serious infections can penetrate tissue, migrating into the bone and other vital

Pathogens and Virulence Factors of Methicillin-Resistant S. Aureus (MRSA):

Strains of Staphylococcus Aureus that exhibit resistance to methicillin; most are resistant to other antibiotics, too

Epidemiology of Methicillin-Resistant S. Aureus (MRSA):

• Usually acquired by elderly and immunosuppressed patients in hospitals and long-term healthcare facilities ( HA-MRSA)

• Can occur in otherwise healthy people in the form of serious skin, soft tissue, and/or pneumonia-like infections ( CA-MRSA; community-associated MRSA)

Treatment and Prevention of Methicillin-Resistant S. Aureus (MRSA):

• - Typically, treated by draining and debriding abscesses, plus vancomycin and/or cocktails of other antibacterial drugs

• Vancomycin-resistant MRSA, or Super-MRSA, now becoming particularly problematic.

Necrotizing Fasciitis: Signs and symptoms

Intense pain and swelling due to digestion of muscle fascia by the bacterium, easily misdiagnosed

EXTREME PAIN! PAIN OFF THE CHARTS

Pathogen Factors of Necrotizing Fasciitis

• Caused by Streptococcus pyogenes

  • Gram positive coccus, arranged in chains ( pealrs)

Virulence Factors of Necrotizing Fasciitis

Enzymes: hyaluronidase breaks down tissue, streptokinase dissolves blood clots

Phagocytic Factors: M. Protein interferes with phagocytosis

Toxins:

1.) Exotoxin A causes toxemia and an overreactive immune response

2.) Streptolysin S kills cells, other pyrogens, stimulate fever, rash, and shock

Pathogenesis and Epidemiology of Necrotizing Fasciitis

• S. pyogenes enter and breaks in the skin and will secrete enzymes and toxins

• Will destroy tissues at a rate of centimeters per hours

• Group A streptococci usually spread from person-to-person

• about 15% of people with this infection will die

Diagnosis, Treatment, and Prevention Necrotizing Fasciitis

• Difficult to diagnose in the early stages because the symptoms are nonspecific and flu-like

• Treatment: clindamycin and penicillin often after very aggressive removal of infected tissues

Early treatment is vital

Acne: Pathogen and Virulence Factors

Caused by Propionibacterium Acnes in 85% of cases

Propionibacterium acnes: Gram-positive, rod-shaped diphtheroid that grow within sebaceous glands and lives on secreted sebum

Epidemiology of Acne:

• Propionibacterium are normal microbiota

• Begins in adolescence, can occur later

Acne: Diagnosis, Treatment, and Prevention

• Diagnosed by visual detection of the skin

• Treat with antimicrobial drugs, drugs that cause exfoliation, retinoic acid for sebum inhibition ( Accutane), or blue light exposure to destroy P. Acnes

Cat Scratch Fever: Signs and SYmptoms

• Fever malaise, localized swelling at the site of infection and red papule

• Atypical cases involve organ symptoms.

  • Optic nerves, Encephalopathy, and meningitis

Cat Scratch Fever: Pathogen and Virulence Factors

• Bartonella henselae: gram-negative bacteria that possess the endotoxin “lipid a”

  • barontella can grow inside RBC and within the lining of blood vessel walls

Cat Scratch Fever: Pathogenesis and Epidemiology

• Red papule, 1-2 weeks after contact

• Cat scratches, bites, or by blood-sucking arthropods such as a flea

• 22,000 children are infected yearly

Cat Scratch Fever: Diagnosis, Treatment, and Prevention

• Positive Fluorescent Antibody Test

• Antimicrobial Macrolide azithromycin

• Stay away from Cats and clean cat wounds

Some virulence factors of S. aureus are

resistant to some beta-lactam antibotics

Nosocomial Infection

Hospital Acquired Infections

MRSA is more common today in these areas?

Dormitories

Prisons

Contact-to-contact sports like wrestling

Pseudomonas Infection: Sign and Symptoms

Fever, chills, shock, and sometimes a green color due to the pigment pyocyanin

Pseudomonas Infection: Pathogen and Virulence

Pseudomonas Aeruginosa bacterium:

• Diversity of metabolism

• Found in soil, decaying matter, and the other moist environments

Pseudomonas Infection: Virulence factors

• Various adhesions, toxins, and polysaccharide capsule

• Elastase: can degrade components of the IM System

• Produce toxic forms of oxygen that destroy the cell

Pseudomonas Infection: Pathogenis

• Infection can occur in burn victims when bacteria grow under the surface.

• The bacteria kills cells ,destroys tissues, and triggers shock

Pseudomonas Infection: Epidemiology

• P. Aeruginosa is rarely part of the microbiota; it can cause infection throughout the body once inside

• Most burn victims and C.F patients are infected.

• Opportunistic pathogen and is found in most cases of immunocompromised patients

Pseudomonas Infection: Diagnosis, Treatment, and Prevention

-Diagnosis Difficult: pyocyanin discoloration ( green) = massive infection

- Treatment is complex due to the resistance of P. aeruginosa to multiple drugs and disinfectants

• Been found live in disinfectants

• Biofilms

Is P. Aeruginosa widespread?

Yes, it is widespread, and thus infections are not easily prevented; they typically don’t occur

Can Pseudomonas survive in bleach?

Yes, it can survive in bleach

Gas Gangrene: Causative Agent

Clostridium so.: anaerobic Gram-positive bacillus that formed endospore

Gas Gangrene: Portal of Entry

Introduction into dead (necrotic) tissue via traumatic event

Gas Gangrene: Signs and Symptoms

Pain and swelling at the injury site, fever, crackling sounds and bubbles at the site of infection, foul-smelling drainage, tachycardia

Gas Gangrene: Incubation

1 to 3 Days

Gas Gangrene: Susceptibility

The presence of deep, lacerating wounds

Gas Gangrene: Treatment

Surgical removal of dead tissue and antibiotics treatment

Gas Gangrene: Prevention

Proper cleansing of wounds

Smallpox

• 2-3 days severe illness before rash

• Lesions first appear in mouth face, and most concentrated on face, hands, and feet

• Lesions develop at once and look alike on any part of the body

• Lesions change slowly, scabbing over after 9-15 days

• lesions firm, dome-shaped, and deep in skin

• Rash common on palms and Soles

Chickenpox

• 0-2 days mild illness before rash

• Lesions first appear on face, trunk, and often “ patchy” and most concentrated on torso

• Lesions develop in successive crops with some new, some crusting

• Lesions changed rapidly, crusting over within 24 hours

• Lesions are superficial pustules like water droplet on flower

Smallpox: Cause

Orthopoxvirus ( Variola virus)

Smallpox: Portal of Entry

Inhalation of viral particles

Smallpox: Signs and Symptoms

Rash that develops into papules, vesicles, and then pustules

Smallpox: Incubation

12-14 days

Smallpox: Treatment

Immediate Vaccination

Smallpox: Prevention

Vaccination discontinued in U.S in 1972

Poxvirus Diseases ( Smallpox)

Smallpox is the first human disease eradicated

Diseases progresses in stages

Poxviruses that can cause human diseases

• Smallpox

• Cowpox ( infects humans rarely)

• Monkeypox

Stages of Poxvirus

Smallpox Progression:

Papular Stage: 3 days after onset of fever

Pustular Stage: 9 days after onset of fever

Chickenpox and Shingles: Cause

Varicellovirus ( varicella-zoster virus, VZV); part of the Herpes family

Chickenpox and Shingles: Portal of Entry

Respiratory Tract —> Blood ( liver/ spleen) —> nerve ganglia (latent). Shingles may develop in ¼ of cases

Chickenpox and Shingles: Signs/ Symptoms

Characteristic rash (CP), Location of the body & AB test (Shingles)

Chickenpox and Shingles: Incubation

2- 3 weeks

Chickenpox and Shingles: Susceptibility

Unvaccinated individuals and those who never had it

Chickenpox and Shingles: Treatment

Relief of Symptoms

• Loose fitting cloths and Acyclovir “ rash pain”

Chickenpox and Shingles: Prevention

Attenuated Vaccine

Do not give aspirin to children

Reye’s Syndrome can occur after Chickenpox infection, what does it affect

The liver and brain

Herpes Infections: Signs and Symptoms

• Malaise, fever, muscle pain and blister

• Characteristic slowly spreading skin lesions.

• Infection also occurs at various other body sites

• 2/3 herpes infections result in the recurrence of lesions of latent virus

Herpes Infections: Portal of Entry

• Break in the skin or mucous membrane.

  • Virus will enter sensory nerve cells ( latent)

  • Upon stress, the virus will travel down the nerve to form a recurrent lesion

Herpes Simplex-1 (HSV-1): Epidemiology

Occurs via casual contact/ by age 2 & 80% of children are asymptomatic

Herpes Simplex Virus-2 ( HSV-2): Epidemiology

Most infections: Sexual contact, 15-29 years old

Diagnosis, Treatment, Prevention of HSV-1 and HSV-2

Diagnosis made by the presence of characteristic lesions

Immunoassay reveals presence of viral antigens

Chemotherapeutic drugs can help control the disease, but they DO NOT CURE IT

Warts: Cause

Caused by various papillomaviruses that are transmitted via direct contact and fomites

How many types of Human papillomavirus?

60 known types

Warts are typically seen as:

benign growths of epithelial layers of the skin

Some strains of Human papillomavirus contain what?

Oncogenes

How is Warts (HPV) diagnosed?

• Direct observation

• Various techniques to remove warts are available, though new warts can develop due to latent viruses.

  • Cryosurgery, Laser, Salicylic Acid, Duct Tape

Warts are formed on many body surfaces, what are these surfaces?

• Hands and feet ( cool body reigions)

• External Genitalia ( Genital warts)

• Cervix

HPV ( Warts) enters through a break in the skin and infects what?

Epithelial layers and Mucous cells

Latent HPV may lead to cervical cancer in women

• Not all cervical cancers are caused by HPV, and not all HPV’s cause cervical cancer.

Gardasil vaccine ( Merck) provides immunity to what?

Four HPV’s that cause 70% of cervical cancers and 90% of genital warts worldwide

7 Types of Coronaviruses:

1.) 229E ( alpha coronavirus)

2.) NL63 ( alpha coronavirus)

3.) OC43 ( beta coronavirus)

4.) HKMU1 (beta conversion)

5.) SARs-CoV-1

6.) MERs

7.) SARS-CoV-2

Coronoavirus will cause symptoms of the common cold of the upper respiratory system, but when were they first identified?

In the mid 1960s

Three Viruses of Coronavirus that can cause serious and fatal infections

1.) Sars-CoV-1

2.) MERS

3.) SAR-CoV-2

SARs-CoV-1

• Originated in China in 2002

• Likely originating in bat population

• 8098 infected/ 774 deaths ( 9.6% mortality rate)

MERS

originated in Saudi Arabia in 2012

2566 infected/ 882 deaths ( 35% mortality rate)

SARS-CoV-2

• Originated in Wuhan China in 2002

• 32.6 million infected/580K deaths in the U.S ( 1.8% morality rate) as of 12/21

• The CDC has identified the Delta and Omicron strains as variants of concern

• As of January 2022, the omicron variant has caused more than 96% of COVID-19 cases in the United States

Pathogenesis of COVID-19

Attachment occurs between the virus spike protein and the ACE-2 receptor on the host cells.

Angiotensin-converting enzyme 2 (ACE-2)

• primary located in the lungs, colon, and heart tissues

• This enzyme is involved in regulation of blood pressure

• Secondary locations are in the nose, mouth, and oral mucosa

How does COVID-19 look like at the cellular level?

Virus gains entry to lungs —> Viral replication would occur at the alveolar Type II cells —> Damage of the alveolar cells lead to an inflammation response

Severe damage is known to induce a cytokine storm

What is a cytokine storm?

Causes acute respiratory distress syndrome, blood clotting events such as strokes, myocardial infarction, kidney, liver, and other organ disfunction